1. Field of the Invention
The present invention relates to high-voltage direct current interrupting devices, and particularly to such devices of the type comprising a commutating circuit-breaker with two parallel branches, one branch consisting of a series connection of a capacitor and a spark gap device, and the second branch consists of a surge diverter arranged to control the current and interrupt it upon opening of the commutating circuit-breaker.
2. Prior Art
High-voltage direct current interruption devices of the above-mentioned type are known, for example, as described in U.S. Pat. No. 3,809,959, wherein the spark gap connected to the capacitor is severely worn because of the high currents passing through the spark gap during the breaking operations. This causes the spark gap ignition voltage to vary within relatively wide limits, and such variations of the ignition voltage must be taken into consideration when dimensioning the commutating circuit-breaker and the capacitor so that a safe current commutation to the capacitor branch is obtained both at the lowest and the highest ignition voltage that may occur. Those considerations increase the costs and the size of the capacitor and the commutating circuit-breaker.